Clock with plug-in key



y 0, 1955 H. JUNGHANS ETAL CLOCK WITH PLUG-IN KEY Filed July 26. 1951 S 1. a M i i IF:

Unite States Patent Oflice 2,707,861 Patented May 10, 1955 CLQCK WHTH PLUG-IN KEY Helmet Junghans, Eclrenhof Schi'amberg=Snlgen, and Leo Harmer, Schramberg-Wurttemberg, Germany, assignors to Gebrnder Juughans A. G., Schramberg, Geishaide, Germany, a German company Application .luly 2-6, 1951, Serial No. 238,612 Claims priority, application Germany July 26, 1950 4 (Ilaims. (Cl. 58-46) The invention relates to clocks which are wound by a key inserted through the dial plate.

in clocks of this nature, the winding shaft is generally made as the male member and the key the female member. The diameter of the opening in the dial plate must also take into account deviations from the central position with respect to the winding shaft, and must therefore be made comparatively large, thereby impairing the appearance of the clock face. A shaft diameter frequently used with winding keys is about 8 mm.; the hole in the dial plate must then be at least 9 mm.; if it is recessec for the purpose of better appearance, the diameter of the socket is about 10-11 mm., and thus the area of the opening in the dial plate is about 80 mm.

it is an object of the invention to obviate this disadvantage by modifying the clock and the winding key and to impart a more pleasing appearance to the clock. For this purpose, according to the invention, the winding shaft is made as the female member, and the shaft of the winding key is made as the male member, the openings in the dial plate only being made sufficiently large for the key shaft to pass through.

By this means, it is possible, especially when the material used for the key shaft is of high strength, to reduce the cross-section of said shaft to such an extent that the openings in the dial plate scarcely detract from the pleasing appearance of the clock. For example, the key shaft can be made as a square stud with an edge length of 4 mm; the diagonal is then 5.7 mm. and it is possible satisfactorily to use a hole diameter in the dial plate of 6 mm. The area of the opening is then about 28 mm. that is to say, less than half the opening in the usual case.

In order to prevent the dial plate from being scratched when introducing the key into the small dial plate opening, it is proposed, according to a preferred form of the invention, that the insertion end of the key shaft should terminate in a truncated point, this point either being polished or consisting of a protective member of rubber, synthetic material or the like fitted on the shaft.

In order to explain the invention, one embodiment thereof will now be described with reference to the accompanying drawing, wherein:

Fig. 1 is a simplified section through a clock mechanism with a dial plate, seen from the side;

Fig. 2 is an elevation of a winding key;

Fig. 3 shows a second form of the shaft of the winding key.

Fig. Fig. 2.

As a result of omitting the parts not essential to an understanding of the invention, only the frame 1, the winding shaft 2 and a spring casing 3 are shown of the clock mechanism; 4 is the dial plate.

4 is an enlarged detailed View of a portion of The winding shaft 2 is formed at its end facing the dial plate 4 with a square hole 211 into which fits the shaft 5 of the Winding key 6 (Fig. 2), said shaft being constructed as a square stud. The cross-section of the key shaft 5 is kept as small as permitted by the strength of the material under the given force conditions. Of correspondingly small size is the hole 4a in the dial plate for the insertion of the key shaft 5, so that by having as small as possible an opening, the pleasing appearance of the clock is not spoiled.

in order to avoid damaging the dial plate upon insertion of the key shaft 5 into the winding shaft 2, the free end of the key shaft 5 is formed with an undercut pin 50, over which is drawn a protective cap 7 of soft material, for example, rubber, or a suitable type of synthetic material.

in the second embodiment of the key shaft 15 as shown in Fig. 3, the end 15a forms a part of the shaft; in order to avoid damaging the dial plate with such a key, the end 1511 is tapered and polished, and may also be rounded off.

The invention can be used with advantage not only with clocks which are wound by inserting a key through a hole in the dial plate, but also with such constructions in which the winding holes are located at another place On the clock casing Where they detract from the pleasing appearance of the clock.

We claim:

1. in a clock in which the winding key having a square end is applied from the dial side, a winding arbor having a square end hole therein as the female part of the winding mechanism cooperating with the squareended winding key, the latter representing the male part of the winding mechanism, the dial having a hole therein for inserting the winding key, said hole being of a diameter smaller than the outer diameter of the winding arbor-end, the distance of the said end of the winding arbor from the rear-side of the dial being smaller than the radius of the end of the winding arbor.

2. Winding key for clocks according to claim 1, having a tapered end on its key shaft facilitating the insertion of the key into the square hole of the end of the winding arbor.

3. Winding key for clocks according to claim 1, having a rounded and polished end on its key shaft facilitating the insertion of the key into the square hole of the end of the winding arbor.

4. Winding key for clocks according to claim 1, having a key shaft provided with planar faces for engagement with the square hole in the end of the winding arbor, a reduced portion in the form of an undercut pin on the free end of said key shaft, and a protective cap fitted over said reduced portion, said protective cap being of a material softer than that of the clock face.

References Cited in the file of this patent UNITED STATES PATENTS 197,969 Ellis et al. Dec. 11, 1877 820,669 Porter May 15, 1906 1,056,364 Porter Mar. 18, 1913 1,533,529 Wehinger Apr. 14, 1925 2,121,197 Jackson June 21, 1938 2,541,431 Meehlbauer Feb. 13, 195] FOREIGN PATENTS 470,238 France Mar. 30, 1914 

